A wide variety of blade shapes have been designed for use in low pressure applications of axial impellers over the years. Blade parameters such as camber, pitch, and chord have of course been varied in arriving at desired impeller performance characteristics. While a "cut and try" design technique has probably been most commonly employed more sophisticated design methods such as a "Free Vortex" design technique have also been used. The resulting blades and impellers have been generally satisfactory but one or more problems of excessive size, noise generation, vibration, etc. is usually encountered in operation.